Project Summary: The striatum is implicated in learning, reward and addiction, including alcoholism. Within the striatum, ablation of cholinergic interneurons (CINs) results in behavioral and cognitive deficits similar to those observed in alcoholics. Interestingly, there is evidence indicating a decrease in CINs following chronic ethanol exposure. In agreement, I have found that striatal cholinergic function is impaired in monkeys following long-term ethanol consumption. Therefore, the overarching hypothesis of this proposal is that chronic ethanol exposure decreases striatal CIN numbers or function and that these ethanol-induced cholinergic impairments underlie the behavioral and cognitive deficits associated with alcoholism. To test this hypothesis, I propose three specific aims: Specific Aim 1 ? I will determine the effect of acute ethanol on striatal CIN subtypes using transgenic mice, immunohistochemical, RNAscope, and electrophysiological techniques. The characterization of CIN subtype sensitivity to ethanol will be of broad interest to alcohol and basal ganglia researchers alike. Specific Aim 2 ? I will determine if chronic ethanol-induced deficits in striatal CINs are due to a loss of CINs, an impairment of CIN function, or both. There is agreement in the literature that the striatal cholinergic circuit is hypo-functional following chronic ethanol exposure but the source of this dysfunction is not clear. Therefore, I will determine if CINs are lost and/or if CIN function is compromised (with electrophysiology) following chronic ethanol exposure. These results will be the first to examine the effects of chronic ethanol on striatal CIN function. Specific Aim 3 ? I will then determine if in vivo chemogenetic manipulation of CIN activity after chronic ethanol are sufficient to ameliorate the behavioral and cognitive deficits that accompany chronic ethanol exposure including ethanol consumption and performance on an operant reversal learning task. Throughout my career, I have been interested in the mechanisms underlying normal and aberrant behaviors. I have been fortunate to have mentors that taught me the skills required to engage in meaningful research. At every stage of my career, I have advanced in my technical ability and scientific sophistication and as I continue to train, my mentors, Kim Blackwell and David Lovinger, will challenge me to constantly improve as a scientist and to ask impactful questions, to design compelling experiments to address those questions, and to present my findings clearly and effectively in manuscripts and presentations. Furthermore, we have a plan to ensure that I receive training to conduct exciting experiments, run a successful lab, and mentor trainees. In addition, Drs. Adron Harris and Marisa Roberto, two successful researchers, have agreed to serve on my advisory committee to ensure that I am successful in my transition to an independent investigator. Thus, I am confident that with the mentorship of my mentors, my extramural advisory committee, my technical consultants, and the institutional support of NIAAA and George Mason University, I will be able to execute the proposed experiments, attain a faculty position, and thrive as a successful independent neuroscientist.